I wrote a blog article a while back on the theory on surrogate keys based around Codd and Date.

The link: http://sqlblogcasts.com/blogs/tonyrogerson/archive/2010/03/13/database-design-surrogate-keys-part-1-of-many-rules-for-surrogate-keys-e-f-codd-and-c-j-date-research-and-problems-they-solve.aspx

Reminds me - I need to go back and finish the other parts I said I would.

Surrogates are a good thing and save us from all sorts of problems.

Tony.